


Best Birthday Ever

by preyforme



Series: Cassy Baby [2]
Category: Supernatural
Genre: Anal Fingering, Blow Jobs, Cas turns five!, Dean has a special present for him, Dry Orgasm, Extremely Dubious Consent, Extremely Underage, F/M, Innocent Castiel, Lactation Kink, M/M, Multi, Rimming, Seriously dirty. Not even kidding., Sex Toys, Sibling Incest, Underage Kissing, Underage Sex, You Have Been Warned
Language: English
Status: Completed
Published: 2014-09-14
Updated: 2014-09-14
Packaged: 2018-02-17 10:23:34
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,916
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2306303
Author URL: https://archiveofourown.org/users/preyforme/pseuds/preyforme
Summary: <blockquote class="userstuff">
              <p>Castiel turns five and his big sister Anna and her boyfriend Dean give him a present he'll never forget.</p><p>**EXTREMELY UNDERAGE SEX** PLEASE READ THE TAGS!</p><p>Part two of a series based on the spn-kinkmem request:  "Teen Dean likes sucking his gf's brother's tiny prick. He's so precious. So gorgeous when he orgasms (dry of course). He likes kissing the boy too, fucking his mouth with his tongue. Cas always giggles and makes yummy sounds. Maybe rimming happens too?"</p>
            </blockquote>





	Best Birthday Ever

**Author's Note:**

  * For [PlacingPandora](https://archiveofourown.org/users/PlacingPandora/gifts), [BebeSeeD](https://archiveofourown.org/users/BebeSeeD/gifts).



> This story involves sexual acts between two teenagers and a five year old. Although it is (mostly) "consensual" in the way that he doesn't resist, no one that young can actually give consent. IF YOU DO NOT WANT TO READ ABOUT SEX BETWEEN A CHILD AND TWO ADULTS PLEASE LEAVE. 
> 
> Actually, if you're even a little concerned that there might be a Hell, you should probably leave. This is... explicit. To say the least.
> 
>  
> 
> This is for the amazing PlacingPandora, because without her, this would have never been written. And for BeeSeeD, because her bookmark tags always make me smile.

When Castiel turned five they had a huge party at the church, over half the parishioners attended. There were more pizza boxes than he could count and a bouncy house and the biggest cake he’d ever seen. Even Dean came, who Cas had taken to idolizing, which amused his parents to no end. Dean whispered in his ear that he would get his present later, when they were all alone. But only if he was good and only if he made sure not to tell anyone about the big boy game they played with Anna.

It only took a week for Anna to get babysitting duty. Her parents were celebrating their anniversary and would be gone very late. Anna assured them that she didn’t mind watching her little brother, and Dean had even offered to come over if she got scared being in the house all alone.

They had only been gone for just over an hour when Dean showed up, a small bag in his hand and a chaste kiss for Anna. Cas grinned at the bag and tugged at the hem on Dean’s shirt, “Is that my present??” 

His eyes were even brighter when he was excited and all Dean could do was grin at him, “Maaaaaybbbeee.” He said, teasing the boy gently, “Have you been good? Do you deserve a present?”

He nodded spastically, hair falling down into his eyes, “Yes. I promise. I’ve been a good boy!” He looked over at his big sister, “Right Anna?? Tell him!”

Anna leaned down and scooped the boy up into her arms, grinning at him as she cuddled him close. “You sure have.” She settled him against her hip, he was small for his age but still a little too big to be carried, “Should we show him what we’ve been practicing?”

Cas nodded and reached out for his sister’s face, he cupped both her cheeks and leaned in to kiss her. It was just a peck on the lips first, much like the way Dean had greeted her, then he deepened it, pushing his tiny tongue into her mouth like they’d taught him all those weeks ago.

Dean’s groan was audible through the living room, it was so hot to watch his goody-two-shoes girlfriend make out with her five year old brother. And he looked much more comfortable doing it now, which means they had been practicing. He wrapped his arms around both of them, kissing Anna on her temple before leaning in to kiss Cas on his lips, “You’re not tryin’ to steal my girl, are you?” He was laughing as he asked, running his hand through Cas’s unruly curls as he spoke, obviously a joke. 

“No, he’s tryin’ to steal my man!” Anna joked back as Cas made grabby hands at Dean so he would take him from Anna. “He said he wanted to learn so he could be better at the game next time we played.”

Dean settled the young boy on his hip, his strength made carrying the boy much easier so they made their way towards Cas’s bedroom as they chatted, “Really bud? You practiced just for me?”

Cas nodded and cupped Dean’s face the way he had cupped Anna’s and leaned in to kiss him right there in the hallway. He had gotten much better at kissing and he wondered how often he and Anna did this. There was still too much spit but his lips were so plush and his tongue was so tiny, he could overlook everything else. Cas pulled back with a confident grin on his face, Dean couldn’t help but lean back in to kiss him again, “Much better bud! You’re going to win again for sure!”

“I have another game I want to play with you, okay? It’s like the first one but it feels even better!” Dean set Castiel down on the bed and knelt on the floor, looking up at the small child. He could see how excited Cas was and it was nothing compared to how excited he and Anna were. As a matter of fact, it was all they could talk about anymore, even while they were fucking they were talking about all the things they wanted to do to Cas once they got him alone.

Cas’s eyes went wide, “Even better than last time? How could it feel more better??”

Anna leaned in and kissed him on the tip of his nose, “Let’s get you undressed and we’ll show you. Sound good?” She was tickling his sides as she asked, so instead of answering he just giggled and trashed around on the bed. Anna made short work of pulling his shirt off, running over hands over the indentations of his ribs. She didn’t play with him when Dean wasn’t around. Just a little kissing and touching when she was bathing him. It wasn’t nearly as fun without Dean. 

Dean told Cas to scoot back and lie on the bed, he popped the button open on his shorts and brushed his thumb over the front of his little briefs. The only thing hotter than his tiny cock, was his tiny cock covered by Batman underwear. “Let’s get all these clothes offa you. I want to see how much you’ve grown since you turned five!”

It had only been a few weeks since the first time they played but he swore Cas was growing. As soon as the little boy was completely disrobed Dean just sat back and looked him over from head to toe. He loved the dip of his bellybutton and the way his tiny dick and balls were nestled in between his chubby thighs. He ran a finger over his chest, around his nipples, against his bellybutton and across his soft shaft, “You’re so beautiful.” He looked over at Anna, who was sitting on the other side of the bed, “Isn’t he gorgeous, baby?

Anna had been drinking in the sight of her two boys, she sighed softly and nodded her head, “He looks good enough to eat.” Her manicured fingers joined Dean’s, mapping out his body. She leaned over and captured a tiny nipple in between her teeth, working it over gently before looking up at Cas, “I was right, you’re yummy!”

“You can’t eat me, Anna!” he said with a soft smile, his tiny moans dying down when Anna moved her mouth away from his body. 

“What if we make it fair?” Dean asked with a twinkle in his eye. He reached over to pinch one of Anna’s nipples over her shirt. “You tried to eat him up Anna, it’s only fair that he gets to try to!” Dean wasn’t sure if she’d go along with what he was planning. They’d never been exposed in front of the boy, they’d only touched, tasted. 

Dean wasn’t sure why he worried, Anna didn’t even hesitate. She pulled her shirt off and her red hair fell around her pale shoulders. Before Dean could prompt her for more, she reached behind her thin frame and unclasped her bra, letting her breasts fall free. 

Anna’s breasts were among Dean’s favorite features. They weren’t overly large, about a handful each. Just enough to hold onto while he was fucking her. He reached over and cupped her breast, squeezing it gently before thumbing over her nipple. “Have you ever seen a girl’s boobies before, Cas?” he looked down at the boy, who was more curious than anything else. 

The little boy shook his head, unable to take his eyes away from his big sister’s nude chest. Dean grinned and released his hold on Anna, instead he reached for Cas’s small hand, leading it up to his sister’s breast. Anna gasped softly, eyes fluttering shut as Cas fondled her. His hand was so small, so warm against his skin. Her pussy was dripping wet.

“Anna tried to eat you up, why don’t you try to eat her up?” he watched at the little boy cupped his sister’s breast, obviously not wanting to hurt her. Dean ran his hand up and down Castiel’s thigh, trying to soothe him, “It’s okay, you won’t hurt her. Right Anna?”

Anna smiled down at her baby brother, “You know that babies drink from their mommy’s boobies, right Cas?” Again his only response was nodding, “This will be just like when you were a baby and you drank mommy’s milk.” Anna threaded her hand through the back of Castiel’s hair and gently raised his head as she lowered her body down closer to him. She held her breast in one hand and lead it towards his mouth. “Get it nice and wet Cassy baby.” She was whispering now as his tongue darted out to lap at her skin. She immediately gasped, eyes looking over as Dean’s as Castiel’s mouth closed around her nipple. 

Her hand fell from her breast to his face, she brushed her thumb across his cheek, “Suck on it Cas. Like you’re a baby and I’m your mommy.” 

Her eyes rolled back into her head, looking completely blissed out. She was squeezing her thighs together, trying to get some friction against her clit. “Touch me Dean.” She whimpered, looking over at him, “My pussy is on fire.” 

Dean could barely breathe, just when he thought things couldn’t get hotter, his girlfriend was trying to nurse her five year old brother. He pressed his palm against his cock to relieve a little pressure before reaching under her skirt. Her panties were practically soaked through. He pushed them to the side and shoved two fingers inside her. She was throwing back her head and moaning as she tried to grind down against him. He shook his head, smirking at her, “You’re not getting off that easily. This isn’t about you.” He looked down as Castiel with a fond smile, “This is your birthday, right buddy?”

His fingers slipped from her opening, he toyed with her clit a bit before pulling his hand away completely. Castiel released her breast to grin at Dean, “Yeah! I want my present!”

Dean’s hand was slick with Anna’s pussy juice and he used it as lubrication to start fondling Cas’s little dick. He got hard almost immediately, tiny body not used to being touched in such a way. “His little prick is hard and it smells like your pussy. Tell me that isn’t the hottest thing ever.” He used his free hand to tug Anna’s hair, pulling her closer as he stuck his tongue down her throat. He kissed her passionately, wanting to remind her that although playing with Cas was fun, she was the one that he loved. 

He released her and bent down to take Castiel’s hard dick into his mouth. He had never been attracted to men, but there was something about an underdeveloped dick. Something about having a prick in his mouth that hadn’t even been through first grade yet, it made his own dick leak. 

Lapping at the child’s tiny balls he took his entire package in his mouth once again, remembering how much Anna liked seeing it last time. He worked his tongue over the shaft, down his balls to his perineum. Cas was fidgeting underneath him already, Dean backed off, he didn’t want the boy to come too soon. 

Dean’s tongue sunk down further, lapping at his tiny entrance, this time he pushed his tongue into the tight ring of muscle. Cas’s eye’s flew open immediately, “Dean?” his voice was quiet and shaky, obviously unsure of what was going on. 

Anna kissed his forehead and reached down to stroke his dick again, knowing that would calm him down. “Dean won’t hurt you, you know that Cas. Just relax.” 

Cas didn’t look completely convinced but he nodded his head and tried to stay still for Dean. He felt something hard enter his bum and he wasn’t sure what it was. It didn’t hurt but it didn’t feel very good either. “Dean. I don’t think I like this.” His voice was trembling, he didn’t want to disappoint Dean. He wanted to be a big boy and play big boy games but he wasn’t sure about what was going on.

Dean had been working his pinky finger into Castiel’s hole when he started to sound more scared than aroused. Dean’s finger stopped moving but he didn’t take it out. Castiel’s ass was so tight, Dean knew it’d be years before he could fuck it but he wanted to show Cas how much pleasure could come from that part of his body. He leaned up and kissed Cas’s soft tummy then over his heart, then on the lips, “Cas, I know it feels funny but I promise it will feel really, _really_ good in a few minutes. Just lemme try, okay? If it hurts, I’ll stop. I promise.”

Cas really wanted Dean to like him so he nodded and squeezed his eyes shut, this body tensed for a moment and Dean groaned again. Cas was so hot and tight around his little finger, he could only imagine how hot and tight he’d be around his cock. 

He worked his finger in and out of Cas’s body, gradually he relaxed and looked less afraid of the situation. Finally Dean upended the bag and out rolled a bottle and a tiny cylinder smaller than a tube of lipstick. “That’s my present?” both confusion and arousal thick in his voice. 

Dean looked up at Anna, shock and arousal present in her face as she realized what Dean had brought. “Yup, I promise you’re gonna really like it!” 

Dean opened the bottle of lube and drizzled it right onto Castiel’s tiny prick that his sister had taken to lazily stroking and twisting, watching how excited her little brother could get from his sister’s fingers. He shivered, gorgeous blue eyes wide as he looked up at Dean, “S’cold.” Dean grinned and worked it over his skin, noticing immediately how much the boy enjoyed the slickness against his tiny cock. The lube leaked lower over his tiny balls and started pooling at his entrance. Dean had used way too much lube but he liked Cas like this; slick and messy. Like Anna’s pussy.

He pushed a finger into Cas’s opening and thanks to Dean’s prep it went in fluidly. He twisted and turned the digit, not sure if a child so young could experience pleasure from his prostrate but determined to find out. When he did _something_ that caused Cas’s entire body to seize up he knew he found the boy’s button. He grinned and pulled his finger out, rolling the cylinder in the lube before pushing it into Cas’s entrance. “Dean? Wha’that?” he slurred, speech soaked in lust.

Instead of answering, he flicked a switch on the bottom of the toy and it began vibrating inside his tiny asshole. Cas started thrashing around immediately, moaning Dean’s name loudly as his virgin hole was being invaded by the toy. Dean groped Cas’s balls while Anna jerked him off in earnest. 

Dean knew Cas wasn’t going to last long so he knocked Anna’s hand away and grabbed her hips, “Get between his legs.” He leaned into Anna’s ear, “Blow him while I fuck your soaking wet pussy. I want us both to come inside you.”

He knew nothing would come out of Castiel’s little prick but the thought that one day they both might blow a load in her at the same time was making him dizzy. He watched Anna wrap her lips around his immature cock, no regard for the lube on his skin as she sucked him down.

Dean’s cock was leaking so much he could feel a spot on his boxer-briefs that could rival Anna’s panties. He got it out as quickly as he could and shoved it into Anna’s went cunt, panties pushed to the side, ass up in the air while her mouth was between her baby brother’s legs. It was a gorgeous sight.

He made eye contact with Cas and watched as his little body trembled and he came, dry, against his sister’s lips. Dean only lasted another stroke or two before he was blowing his load deep inside of his girlfriend.

Dean shifted back to kneel on the mattress, bringing Anna’s hips back with him to keep his cock firmly inside her pussy. Cas looked so blissed out he appeared almost drunk as Dean reached around Anna’s body and eased the toy out of his entrance, “How was that buddy?”

Cas actually laughed, sounding every bit as intoxicated as he looked, “Super duper awesome!”

“Good. I’m leaving the toy with Anna.” Slowly he worked the toy up the inside of Anna’s thighs, under her skirt where he pushed it against her slick clit. He clicked it on away and let it buzz right against her most sensitive area, “You like that baby?” Dean licked a stripe up her neck and bit at her skin, whispering against her ear, “That toy was in your baby brother’s asshole now it’s on your clit. I wanna watch both of you come on my present.”

Anna shook just as beautifully as Castiel did when he came and he finally let Anna shift so his softening dick could east out of her body. “Anna’s gonna keep it nice and safe for you. You can use it whenever your mommy and daddy are gone. Anna will even help you, okay big guy?” 

Cas nodded, eyes fluttering shut, “Okay Dean. Thanks for the best birthday present ever.”


End file.
